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Marine Ecology Progress Series

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MEPS 455:157-172 (2012)  -  DOI:

Krill feeding on sediment in the Gulf of Maine (North Atlantic)

Alison C. Cleary*, Edward G. Durbin, Tatiana A. Rynearson

University of Rhode Island, Graduate School of Oceanography, Narragansett, Rhode Island, 02882, USA

ABSTRACT: Krill are key members of many marine ecosystems, serving as a critical trophic link between microscopic organisms and large predators such as whales, fish, and seabirds. Krill feeding is thus important to ecosystem carbon cycling. Traditional approaches to determining in-situ krill feeding require a priori assumptions, and may have prey-type detection biases. We took a DNA-based approach to measuring in-situ feeding by northern krill Meganyctiphanes norvegica. The diversity of prey consumed by M. norvegica in situ was analyzed for 80 krill at 8 stations throughout the Gulf of Maine (North Atlantic) using peptide nucleic acid mediated polymerase chain reaction (PNA-PCR) clone library sequencing of 18S rDNA. Relative abundance of the 2 most common prey types was measured with quantitative PCR (qPCR) in the guts of 16 krill. The 245 prey sequences recovered from krill gut contents included copepods, salps, phytoplankton, and a poorly known organism found to be sediment associated. Calanus finmarchicus and the sediment-associated organism were found most commonly, at 7 and 8 stations, respectively, and their 18S rDNA was present in nearly equal quantities in individual krill guts. M. norvegica, like most krill, are typically considered planktivorous; thus krill feeding on sediment organisms represents an unrecognized pathway for carbon flow from the sediment to the pelagic. Calculations suggest that this unrecognized pathway could potentially bring over 100000 t of carbon annually back into the Gulf of Maine pelagic ecosystem, equivalent to 4% of annual primary production, or the energy demands of 80% of the region’s fin whale population.

KEY WORDS: Meganyctiphanes norvegica · Gut contents · 18S rDNA · Benthic−pelagic coupling · PNA-PCR

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Cite this article as: Cleary AC, Durbin EG, Rynearson TA (2012) Krill feeding on sediment in the Gulf of Maine (North Atlantic). Mar Ecol Prog Ser 455:157-172.

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